In the manufacture of such light sensitive materials, lengths or webs of film or paper many hundreds or thousands of feet in length are prepared in widths desired for end products and then wound on stock rolls. These rolls are then installed in spooling equipment which removes the web from the stock roll in strips of predetermined length which are then wound onto a spool for eventual use by the customer. For some types of photographic film, the strip is wound onto a spool which is then encased in a light tight magazine or cartridge; while for other types, the strip is wound onto the spool together with a longer strip of light tight wrapper material, typically a special type of paper, thus making unnecessary the use of a further magazine for the wound spool. Films wound in the latter manner with a wrapper material have been used for decades.
FIG. 1 shows an edge view of a strip of film 10 and a strip of protective wrapper material 12, which for ease of illustration and explanation, are shown superimposed on one another in a flattened state prior to winding onto a well-known type of spool 14, shown partially in section. The core 16 of spool 14 comprises an axially extending slot 18; and radially extending flanges 20 are provided at either end of core 16, only one flange being illustrated. In the familiar manner, wrapper strip 12 is provided near its lead end 22 with an after-use label 24 which is used by the customer to secure the wrapper strip about the exposed film after the customer has unwound the film and wrapper from spool 14 and rewound the film and wrapper onto a take-up spool in a camera. Label 24 is applied to wrapper strip 12 before winding onto spool 14. The lead end 26 of film strip 10 is unattached to wrapper strip 12; however, the tail end 28 is attached to wrapper strip 12 during winding by an inside paster strip 30 which typically is attached to film strip 10 just after the strip is cut from the stock roll. Thus, when wrapper strip 12 is wound onto the take-up spool in a camera, film strip 10 is drawn along by inside paster strip 30. Also in the familiar manner, wrapper strip 12 is provided at its tail end 32 with an outside paster strip 34 which secures the wrapper strip about the unexposed film prior to sue by the customer. In the familiar manner, tail end 32 also may be folded back on itself, not illustrated, before outside paster strip 34 is applied, to provide a more convenient finger grip for the customer when opening the spool prior to use.
During winding of wrapper strip 12 and film strip 10, lead end 22 is threaded through slot 18 and spool 14 is rotated clockwise, as viewed in FIG. 2, so that the lead portion of wrapper strip 12 is wound onto core 16. Then, lead end 26 is introduced into the nip formed between the remainder of wrapper strip 12 and the portion already wound onto core 16; so that lead end 26 becomes cinched between convolutions of the wrapper strip, after which the wrapper and film strips are wound together. The wrapper strip eventually is cut and when inside paster strip 30 is drawn into the nip, it adheres to wrapper strip 12. After an additional length of wrapper strip has been wound onto the spool, outside paster strip 34 is applied to complete the process.
In known equipment of the type used to wind film and wrapper strips in the manner just described, the film is drawn from its stock roll by an intermittently operated vacuum drum which feeds the film past a cutting mechanism into a curved guide track until the lead end of the film enters the nip between a pair of resilient rollers. After the film has been cut to form a strip, the rollers are driven to insert the lead end of the film into the nip formed by the wrapper strip in the manner previously described. A disadvantage of the use of such rollers is that they apply pressure to the film which, with modern pressure sensitive films, can lead to pressure induced marks in the processed film. In addition, such rollers tend to scuff the surfaces and edges of the film which also can lead to unwanted defects in the processed film. And, because the rollers must be at a fixed distance from the cutter to acquire the lead end of the film strip before cutting, the position of the rollers must be changed or multiple sets of rollers must be provided if film strips of different lengths are to be cut and fed. Another difficulty of such equipment has been to match the velocities of the wrapper strip and the film strip as the film enters the nip formed by the wrapper strip. If the film strip is moving too slowly, its lead end will not be accurately positioned relative to the wrapper strip, which can lead to misregistration of the film in the camera. If the film strip is driven only slightly faster than the wrapper strip, then a slight negative tension may be applied to the film which can help avoid pressure induced marks. However, if the film strip is moving too quickly, its lead end may stub over on encountering the nip which can cause undesirable irregularities during winding and lead to pressure induced marks.